This invention relates to a lock with facility for preventing unauthorised entry and particularly relates to a lock having elements which are responsive to attempted unauthorised entry by use of a torch or similar heat-generating device for preventing operation of the lock thereafter.
A new method of making an unauthorised entry involves using a miniature welding torch to melt out the lock cylinder or lock tumbler mechanism associated with a lock so as to gain access to a bolt element of the lock. This method of entry is simplified by the fact that the lock cylinder or the lock tumblers are generally produced from brass alloys having a melting point of about 850.degree. C. The bolt element is located in a bolt element operating region adjacent the lock cylinder or lock tumbler mechanism and, consists of steel having a melting point above 1000.degree. C. and is not damaged during the melting process so that the lock can be opened relatively easily after the lock cylinder or the lock tumbler mechanism have been melted out.